It is "in that it makes it possible to realize the impressive scale ratio between the two stars", that the phenomenon is "spectacular", explains the Observatory of Paris on its site.
The phenomenon will be observable from all parts of the globe where the sun will be raised, from 13:35 French time, subject to favorable weather conditions.
In metropolis, the sun will set before the end of the phenomenon
"It will not be visible in its entirety because the Sun will set before the end of the passage, but can however be observed until between 16h48 and 17h32, depending on the region," says the Observatory, referring to metropolitan France.
Overseas, the phenomenon will be visible everywhere, except in New Caledonia.
Safety instructions to follow
If the Paris Observatory provides the keys to contemplate the passage of Mercury in front of the Sun, the astronomers of the structure also recommend several safety instructions to enjoy the show serenely and safely.
"You should never observe the sun without special protection, otherwise you risk serious eye damage," says the Observatory.
"The best method to follow the passage of Mercury without risk is that of an observation by projection on a screen", details the site, or by means of a "magnifying astronomical instrument (…) obligatorily provided with a solar filter of density 5 of the type 'mylar' ".
Eclipse glasses, like those of Soleil, are to be avoided.